New influenza A virus found in bats

Feb 27, 2012 (CIDRAP News) – A research team today announced the discovery of a new influenza A virus in Guatemalan fruit bats, but in its current form the virus doesn't pose a threat to humans, according to the US Centers for Disease Control and Prevention (CDC).

The researchers, who included scientists from the CDC, reported their findings today in Proceedings of the National Academy of Sciences (PNAS).

Suxiang Tong, PhD, the study's lead author and head of the pathogen discovery program in the CDC's division of viral diseases, said in a CDC press release e-mailed to reporters that the discovery marks the first identification of an influenza virus in bats. "The study is important, because the research has identified a new animal species that may act as a source of flu viruses."

The bat influenza virus would need to go through several reassortment steps to infect humans, the CDC said. Early tests suggest the genes of the new virus are compatible with human influenza viruses.

However, Ruben Donis, PhD, a study coauthor and chief of the molecular virology and vaccines branch of the CDC's influenza division, added that initial tests show the virus found in bats would need to undergo significant changes to infect and spread easily among humans. "A different animal—such as a pig, horse, or dog—would need to be capable of being infected with both this new bat influenza virus and human influenza viruses for reassortment to occur."

The researchers found the new influenza A in only one species, little yellow-shouldered bats, which are common in Central and South America but are not native to the United States, according to the CDC.

In their search for novel flu viruses in bats, the research group captured 316 bats representing 21 different species at eight locations in southern Guatemala in May 2009 and September 2010, according to the PNAS report. Using polymerase chain reaction testing, they found positive samples from three bats at two different locations, all of the animals little yellow-shouldered bats.

Genome sequencing found that the virus is different from known influenza A viruses, because its hemagglutinin can be classified as a new and different subtype, designated H17. The neuraminidase (NA) gene is different than all other known NAs. Scientists weren't able to grow the new virus in cell cultures or chicken embryos.

Serologic studies are under way to determine how common the virus is among bats in Central America and other regions, according to the study. Researchers noted that because the virus was found in two different locations at different times, the finding isn't likely to represent an incidental interspecies transfer.

"Bats may now be added to the list of mammalian hosts of influenza A viruses," the group wrote, adding that the finding expands the list of flu reservoirs and raises questions about how the virus is maintained in bat populations and what the findings mean for public health.